The flash flickers or strobes (pre-flash) and there is a delay before taking a picture.

The camera flash will flicker or strobe before taking a picture if it is set to use any of the following modes:

Red-eye Reduction

Pre-flash Metering (TTL or ADI)

AF Illuminator

This is normal operation when a camera is set to use any of these modes. If you do not want the flash to fire before taking a picture, turn off or disable these modes in the camera menu. Be advised, however, that it may take longer and make it more difficult for the camera to achieve focus.

NOTE: If model-specific information is required to turn off or disable these modes, refer to the operating instructions supplied with the product.
Manuals are posted on your model support page.